Explosive means for cutting an electric cable



Dec. 15, 1964 E. E. KlL-MER 3,161,131

EXPLOSIVE MEANS FOR CUTTING AN ELECTRIC CABLE Filed July 1, 1963 INVENTOR. EARL E. KILMER 0 W km 260% ATTORNEYS.

United States Patent Office 3,161,131 Patented Dec. 15, 1964 3,161,131 EXPLOSIVEMEANS FOR CUTTING AN ELECTRlC CABLE Earl E. Kilmer, College Park, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed July 1, 1963, Ser. No. 292,168

Claims. (Cl. 10224) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to explosive cable cutting devices and more particularly to an explosive device for cutting and removing a section from an electrical cable without the aid of a mechanical cutting element.

Prior devices of this general character heretofore devised for cutting a cable usually employed a mechanical cutting element or a shaped explosive charge, as the case may be, to sever the cable. I

These devices are not suitable for cutting on electrical cable containing a plurality of conductors for the reason that, in the case of the mechanical cutter, the severed ends of the conductors within the cable may make electrical contact with one another after the cutting operation, particularly when both of the severed lengths of cable are secured to a cable supporting. structure, such as a cable rack or the like. The use-of a shaped charge for severing the cable is not suitable in a closely confined space by reason of the destructive effect of the explosion of the charge. V

The device of the instant invention possesses all of the advantages of the prior devices and none of the foregoing disadvantages.

To achieve this desirable result the explosive cutter of the instant invention severe the electric cable simultaneously at two discrete points defining the length of a section of the cable to be severed and detached from the severed ends of the conductors in the remaining cable. This result is obtained by employing a single sheet of thin flexible plasticized explosive wrapped about the cable and so configured that thecable is severed in two places as the explosive is fired thereby to remove the section of cable so defined without the aid of a mechanical cutting tool.

One of the objects of the present invention is to provide a new and improved explosive cutter for an electric cable.

Another object is to provide an explosive cutter for severing and removing a predetermined section from an electric cable. 7

A further object is to provide a flexible explosive cutter FIG. 3 is a view of the cable as the cutter explodes;

Referring now to the drawing for a more complete tion indicated generally by the numeral 12. As more clearly shown on FIG. 2 the device comprises a flexible sheet of a thin plasticized explosive comprising two elongated strips 13 and 14 of sufficient length to make two complete wraps about the cable andinterconnected by a first-longitudinal portion 15 at one end thereof and a second longitudinal portion 16 at an intermediate portion thereof, the portions 15 and 16 being at a distance from each other such that the portion 16 is superimposed upon the portion 15 when the sheet is wrapped about the cable. Within the portion 15 are two'closely spaced rectangular recesses 17, eachadapted to receive and retain an electroresponsive detonator 18, FIG. 1, in mutually aligned spaced relation and preferably retained within the recesses by a suitable adhesive applied thereon. The detonators are disposed within the recesses in such manner that'the detonation output from one of the detonators is in faceto-face opposing relation with the detonation output of the other. A pair of firing leads 19 is employed to establish a firing circuit to the detonators substantially as shown.

A small mass of plasticized explosive 21 is disposed between the opposing ends of the detonators and secured to the sheet explosive comprising the longitudinal portion 15 in'any suitable manner as by a bonding cement applied therebetween, thereby to increase the reliability of initiation of the explosive sheet as the detonators are fired.

In the event that, through malfunction or other cause, only one of the detonators should fire, the explosive mass 21 would insure initiation of the other detonator by countermine action. The sheet of explosive comprising the strips 13 and longitudinal portions is preferably 0.050 inch in thickness although, if desired, a somewhat thinner or thicker sheet of explosive may be employed. The explosive mass 21 is preferably comprised of an explosive sheet of the same thickness and characteristics as the main sheet of explosive and, if desired, this small sheet of explosive may be folded over to provide an explosive mass of double thickness. The entire surface of the main explosive sheet is covered with a suitable adhesive whereby the cutter'is tightly bonded to the cable 10, and the longitudinal portion 16 thereof is bonded to the portion 15 when the explosive cutter is wrapped about the cable in the manner shown on FIG, 1. Furthermore, the lower portions of the strips 13 and 14, as viewed in FIG. 2, are securely bonded to the upper portions thereof when the cutter has been wrapped about the cable.

In operation, when the detonators are operated by a firing impulse applied to the leads 19 the longitudinal portions 15 and 16 are initiated thereby causing the annular portions indicated generally by the numerals 22 and 23 of the cutter to be exploded simultaneously, FIG. 3, severing both a length of cable 24 in two places defined by the annular explosives 22 and 23 and the conductors therein and, simultaneously therewith, removing the severed portion 24 from the remaining lengths of cables 25 and 26 in such manner that there is no possibility of continuity of an electrical connection be- I tween any of the conductors of one of the remaining understanding of the invention and more particularly to FIG. 1 thereof, there is shown thereon an electric cable 10 having a plurality of conductors 11 therein about lengths of cable with the conductors in the other re maining length of cable. 7

Whereas the illustrated embodiment of the invention has been described as an explosive cutter having two elongated strips of sufiicient length to make two complete wraps about the cable to be cut, the length of the strips may be such as to provide additional wrappings,

if desired, and where a somewhat less degree of reliability is required, only one detonator may be employed.

Whereas the invention has been described with particularity with reference to an example thereof which gives satisfactory results, it is not so limited, as various changes and modifications will be apparent to one skilled 3 in the art, after understanding the invention, without departing from the spirit and scope of the invention and it is intended, therefore, in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An explosive cable cutter comprising a flexible sheet of explosive configured to provide two elongated portions adapted to be wrapped around and cemented to the cable to be cut and each interconnected at an end portion thereof by a recessed longitudinal portion and at an inter mediate portion by a second longitudinal portion thereby to provide a pair of explosive means tightly encircling the cable at a distance corresponding to the length of said longitudinal portions,

electroresponsive detonating means carried by said first named longitudinal portion within the recess therein in such manner as to engage the cable when the sheet of explosive is wrapped thereabout, said second longitudinal portion being formed at such a distance from the first named longitudinal portion as to be superimposed thereon when the cutter is wrapped about the cable and cemented thereto,

each of said elongated portions being of sufiicient length to provide an explosive wrapping of double thickness completely around the cable thereby to sever the cable in a manner to remove a section thereof defined by said wrapped elongated portions.

2. An explosive cable cutter according to claim 1 in which said detonating means comprise a pair of electroresponsive detonators disposed in end-to-end closely spaced and mutually opposed relation within the recessed portion.

3. An explosive cable cutter according to claim 2 including a small quantity of sheet explosive bonded to said recessed longitudinal portion intermediate said pair of detonators in a manner to be initiated thereby.

4. An explosive cutter according to claim 2 including means for bonding said sheet of explosive to the cable to be cut and maintaining adjacent layers of the explosive sheet tightly bonded together when the sheet has been wrapped about the cable.

5. An explosive cable cutter according to claim 3 in which the bonding means is an adhesive coating carried by the explosive sheet on a surface thereof.

6. An explosive cable cutter comprising a pa l" of elongated strips of flexible sheet explosive of suflicient length to be wrapped at least twice about a cable to be cut,

a pair of flexible explosive means connected to an end portion and an intermediate portion of each of said strips respectively for maintaining the strips of explosive in mutually parallel spaced relation, and

detonating means in the explosive means interconnecting the end portion of each of said elongated explosive strips thereby to cause the cable to be severed by the simultaneous explosion of said elongated strips of explosive wrapped thereabout in a manner to remove the length of cable defined thereby from the remaining lengths of cable. 7

7. An explosive cable cutter according to claim 6 in which the detonating means is a pair of electroresponsive detonators carried by and partially enclosed by the lastnamed explosive means in mutually aligned spaced relation and in subjacent abutting relation to the other explosive means when the cutter is wrapped around the cable to be cut.

8. An explosive cable cutter according to claim 7 including a mass of sheet explosive carried by said lastnamed explosive means and disposed between said detonators from improving the detonating effect thereof.

9. An explosive cable cutter according to claim 8 including means coating the cutter on one side thereof for bonding the cutter to the cable to be cut and maintaining the cutter in a snugly wrapped condition about the cable prior to a cutting operation.

10. An explosive cutter for severing and removing an intermediate section from an electrical cable comprising,

a sheet of flexible explosive configured to form two explosive annuli defining the section to be removed when wrapped about the cable to be cut and having a length of sheet explosive connected therebetween, detonating means disposed within said length of explosive for simultaneously exploding said annuli, and means for bonding said annuli and detonating means to the cable.

References Cited by the Examiner UNITED STATES PATENTS 3,076,408 2/63 Poulter et al 10223 FOREIGN PATENTS 643,556 9/50 Great Britain.

SAMUEL FEINBERG, Primary Examiner. 

1. AN EXPLOSIVE CABLE CUTTER COMPRISING A FLEXIBLE SHEET OF EXPLOSIVE CONFIGURED TO PROVIDE TWO ELONGATED PORTIONS ADAPTED TO BE WRAPPED AROUND AND CEMENTED TO THE CABLE TO BE CUT AND EACH INTERCONNECTED AT AN END PORTION THEREOF BY A RECESSED LONGITUDINAL PORTION AND AT AN INTERMEDIATE PORTION BY A SECOND LONGITUDINAL PORTION THEREBY TO PROVIDE A PAIR OF EXPLOSIVE MEANS TIGHTLY ENCIRCLING THE CABLE AT A DISTANCE CORRESPONDING TO THE LENGTH OF SAID LONGITUDINAL PORTIONS, ELECTRORESPONSIVE DETONATING MEANS CARRIED BY SAID FIRST NAMED LONGITUDINAL PORTION WITHIN THE RECESS THEREIN IN SUCH MANNER AS TO ENGAGE THE CABLE WHEN THE SHEET OF EXPLOSIVE IS WRAPPED THEREABOUT, SAID SECOND LONGITUDINAL PORTION BEING FORMED AT SUCH A DISTANCE FROM THE FIRST NAMED LONGITUDINAL PORTION AS TO BE SUPERIMPOSED THEREON WHEN THE CUTTER IS WRAPPED ABOUT THE CABLE AND CEMENTED THERETO, EACH OF SAID ELONGATED PORTIONS BEING OF SUFFICIENT LENGTH TO PROVIDE AN EXPLOSIVE WRAPPING OF DOUBLE THICKNESS COMPLETELY AROUND THE CABLE THEREBY TO SEVER THE CABLE IN A MANNER TO REMOVE A SECTION THEREOF DEFINED BY SAID WRAPPED ELONGATED PORTIONS. 